Centrifugal casting machine



Dec. 2, 1941. z E. B. MOORE 2,265,043

CENTRIFUGAL CASTING MACHINE Dec. 2, 1941. E. B. MOORE l 22,265,043`

CENTRIFUGAL CASTING MACHINE .Filed April 1, 1940 2 sheets-sheet 2 yf @www Patented- Dec. r2, 1941. 2,265,043

2,265,043 I cEN'ralFUGAL casrmc mesme i namen a Muere, Evanston. nl. Applicaties Apriti, 1940, sei-in No. 327.16

'I'his invention relates to casting'machines of f the centrifugal type-employed in the casting of small articles of gold or othersimilar metals,=as, for example, inlaysory large illlings for dental work,for articles of jewelry.'

One object of the invention is mechanism including rotatable parts whichy are to provide a smooth-running, with a minimum of friction, and

thus adapted to continuel their rotationy for )a1 considerable period after driving impulse. L.

Another object is `cessation of the original ing parts andthe rotatable driving mechanism, to permit said crucible and mold to respond to both centrifugal and inertiaforces, and to assume corresponding positions such as to avoid splashing or spilling or the momen metal during the,

initial portion of the'rotary movement. j

Another object is to provide yielding means 'for controlling such articulation and facilitating return of the partseto the control of centrifugal force when,v the effect of inertia has been .over.

come.

for a given load of 'molten metal of a corresponding mold.

And it isalso *an object of the invention to provide readily adjustable means for releasing the mold or securing it, together with means for engaging the mold, in secured position,'which shall eliminate any possibility of itsescape under the action of centrifugal force during. the-casting operation.

Other objects will appear as lthe Vdescription Vand the weight proceeds. The invention consists in certain features and elements of construction in combination, as herein shown and described and as indi` cated by the claims.

In the drawings:

Figure l is a side elevation of a casting machine embodying this invention, showing the parts as adjusted, readyl for use. l

Figure 2 is a plan section'taken ras indicated at line 2-2 on Figure l to show the motor spring from which the rotary impulse is derived. 4

Figure 3 is atop plan view taken on a reduced scale, indicating approximately the initialpositions assumed by the yparts at the commencement of rotary motion. l

AFigure 4 is a detail'section taken 'as indicated to provide an connection between the crucible and mold-carry.k

A further Objectis to provide means for readily adjusting the mechanism to ay balanced condition f centrifugal I at line on y spring for the hinged mold-carrying arm.

Figure 6 is anaxial vertical section showing y the parts in substantially the 'same positionl `as in Figure 1, and revealing details oi the internal structure.

Figure is a plan ,section taken as indicated atv line 1-1 lon-Figure 6,-' but on a'larger scale.-

Figure is a detail section at the same 'plane as Figure', buton a larger scale.v

Figure 9 is a'detail section taken asfindicated.

Vat line'S--Q'on Figure,6.

' `.Figure 10 is a Figure 6.

Figure 11 is Figure 6."

In the castingv of gold or like metals in producingrelatively small articles, such as dental fillings and .inlayaandsmallpiecesot jewelry, l it is important to transfer the molten metal from j the crucible to the mold quicklyand'under some pressure so as to cause the metal toiow into all parts f; of the mold, including narrow passages and delicatefeatures, and to insure that no air shall berpocketed in the mold. For this purpose `the crucible and moldare frequently mounted i.

' for rotation and arranged so. that the centrifugal expended its force, l so that the centrifugal force i,

may continue to act while'themetal is coolingv force thus generated shall act to transfer the Y metal from the crucible into the moldzand in such apparatus, in order to secure a high initial velocity, it is common to attach the rotatable parts to a motor spring which is -wound up uri--v der tension, and then released suddenly for start-` ing the rotation. A one-way clutch permits the parts to continue rotating after-the spring'has and hardening in the mold. 'In 'a machine of this character it has ybeen a diiiicult problem to initiate the lrotation of the crucible andlmold with the molten metal therein,` suddenly and forcibly, but without causing the metal to splash or spill from they crucible. Certain features of the. present'inventionprovide a successful'solu tion of this problem,v

As shownin the drawings, the machine includes a, hollow base l within which there*is horizontally coiled amotor sprlng' havingfits outer end anchored to theewall of the base'at 3, and with its inner end attached by a stud Ijto a hub 5 -which is journaled for rotation on'an upstanding central stud I fixed inthe base heus-- at lined-4v on Figure 1, showing the relation of the crucible tothe mold ring. Figure 5 is a detail section taken as indicated ing i. A partition `or cover plate 1 is secured directly over the spring 2 to hold it in place, and a sloping cover member I overlies the peripheral Figure 1, shcwmg .the '-rietm detail section schneiti0 on y adetail lsection, at linel Il -II ionA v portion of the partition, said partition and cover being secured to the base housing I by a single set of fastening screws 9.

A cylindrical shell I I extends upwardly from the cover l, and near its upper end supports a nller block II in which there is mounted an annular ball bearing assembly I 2 for a vertical spindle I3 whose lower end is journaled in a bore formed in the stud I, and is stepped upon a steel ball I4 so as to be freely rotatable upon its .vertical axis. 'I'he spindle Il has rigidly pinned in it a clutch collar Il which is provided with ratchet teeth Il formed on its under surface for oneway driving engagement with a clutch pin I 1 yieldingly upheld by a spring I l pocketed in the hub I to which the inner end of the spring 2 is anchored. Thus when the spindle Ilis turned a tooth Il engaging the wind up the spring 2, and then released the spring un- I 1 transmits rapid rotary I3. When the force of the this rotation can continue of the clutch teeth the clutch pin, deits light springll,

when the spindle is winds, and the pin motion to the spindle spring has been spent, because the sloping faces I6* I8 will ride over the end of pressing it in opposition to and permitting the spindle in its bearings.

The upper end of the spindle Ills shown as threaded at I I* to carry a head 2l havinga horizontal bore 2I through which there extends an arm 22 shown as a rod of cylindrical cross-section. This rod is anchored in the head 2l by a cross-bolt 22, and one end of the arm supports a hinged bracket 2l by which the crucible and mold are carried in a manner about to be described. 'I'he other end of the arm 22 carries a weight Nwwhlch is slidably adjustable on the which serves to balance the weight of the parts at its opposite end for insuring relatively smooth rotation of said parts about the axis of the its bearings. The weight 2l is made adjustable because the weight of gold or other metal placed in the crucible, and subsequently transferred to the mold by centrifugal force, will vary in accordance with each particular piece of werk handledr by the machine. The crucible is indicated at 2l, and the mold-carrying ring at 21. With these parts locked in position, and with a quantity of metal in the crucible, it is the usual -practice to apply heat to the metal. as by means of a blow torch or similar device, but before thus melting the metal the parts are balanced about the axis of the cross-bolt 22 to insure proper operation.

portion of the clearanceY space is. occupied by a split tubular collet 2l, having a tapered flange 2l at one end. and being threaded at itsopposite' end. One end of the bore 2| is flared toi) provide a seat for the tapered flange 29 of the collet. and a flare at the other end of said bore 2I provides a seat for the roundedl corner of a reduced' portion Il of the nut ll; thus when the' nut is tightened on the threads of the collet. itdraws the tapered flange 2| of the collet into the flared end of bore 2I. and compresses the collet snugly onto the arm 22, fixing the latter firmly in the head 2l. To permit the parts to be balanced about the axis of the cross-bolt 22, the nut- 2l is unscrewed from the threads of the' collet 2l, or, at least, backed on part-way along said threads, and the clearance slots l2 in the collet, which accommodate the cross-bolt 23,

to continue turning arrangement also involves spindle I I when the latter turns in vu sin 28a which receives the gold n Vreceive the projection 22 by ilrst setting the screw 22 to dimensioned to extend permit the collet to be shifted endwise, away from its tapered seat in the head 2l, leaving the arm 22 free to rock upon the cross-bolt 23, through a limited angle. Static balance is then attained by shifting the weight 2l slidably along the arm 22 until it just balances the parts carried by the other end of the arm; then, preferably, it is moved a trifle farther outward along the arm 22 for more perfectly approximating the condition of dynamic or running balance, and also to compensate for the fact that the metal in the crucible 20 will be transferred outwardly to the mold in the operation of the machine. A pair of set screws 33, 2|, threaded in the weight 25, impinge against. the bottom of a groove or channel 22 in the arm 22 for holding the weight at adjusted position. Preferably, the channel 22* is made of graduated depth. diminishing outwardly, as seen in Figure 1, so that a step-bystep adjustment of the weight 2l may be made the bottom of the channel and then unscrewing it a few degrees, shiftingthe weight 2l outwardly a short distance until a shallower portion of the groove 22 engages the re-adjusted screw 32. then repeating this adjustment, if necessary, until the desired position of the weight 2l is attained. This a safety feature in that it prevents the weight 25 from flying on' the arm 22 if the set screws'should become loosened during operation of the machine. A slight loosening of the screws would merely permit the weight to become wedged a little further outward along the arm 22 by the engagement of the loosened set screw with the bottom of the channel 22* at .a shallower portion thereof. v

A bracket member 2l, carried at the other end of the arm 22, supports a tubular member Il which carries rigidly at its outer end a plate 38 to which there is removably attached, by means of the `bolt I1 and thumb nut Il, a holder 3l for the mold ring 21.` Said ring is a metallic sleeve which seats against the end wall 2l* of the holder I! and lodgestemporarily on its arms Il. At the end opposite the holder 29 the ring 21 is provided with a reduced annular projection 21* which fits an opening in aplate 4l extending parallel to the plate Il but slidably mounted on the arm 2l by means of a sleeve II having aI terminal flange 42 to which the plate Il is secured. This 42, formed to receive the crucible 2l of refractory material. The crucible includes a depressed baor other metal while the heat is applied for outlet port 2lb is arranged somewhat above the bottom of the minates in an annular projection 2l, which is through the plate Il and thus interlap with the the mold ring 21, it being understood that the plaster mold Il, within the ring 21, will include a tapered inlet to the cavity Il* of the mold. and that such tapered inlet will bedimensioned to of the crucible. When commodate the clutch dog I5 which is pivotally under side at 25* to ac-.

about its pivot so as to forcibly engage .a corner or tooth of the dog at its upper end with the inner wall of the tube 35, thus locking 'the sleeve 4l in position. The sleeve is slottedLat-Ji toprovide clearance for the at arm 2'4'b'y which the tubular arm 35 is supported.

The iiat arm 24 is bifurcated at its lower end o to t above and belowl a plate 49 extending rig;-

idly from the en'd of the arm 22, and the twin terminals 49, 49 of the arm 24 are bent to form the tubular portions of a hinge connection between the plate 48 and the arm 24. 'Ihe terminals 49 enclose bushing sleeves 5| and 52 re.

spectively, which are-clamped toopposite faces of the plate 49 by a bolt 53 extendim through the bushings so that the curled terminals 49 are thus Journaled on the bushings 5| and 52 to permit swinging of the arm 24 at an angie to the arm 22.

Such motion, however, is controlled by means of a small coil spring 54, having one end anchored to an inverted cup which is itself anchored to the arm 24 by lugs 56 straddling the arm; the other end of the spring is engaged with a disk 51 which encloses the spring in the cup 55, and is clamped against the end of the bushing 52 by the nut 58 on the bolt 53. A-stop pin 59, de-

pending from the plate 48, limits the swinging movement of the arm 24 about its hinged connection to the arm 22 at a position in which they are aligned, so that the tubular arm 35 is held in alignment with the arm22, and the spring 54 urges the parts to this position. But when the arm 22 is released for rotation by the force of the spring 2, the inertia of the arms 24 land 35, and the parts lcarried thereby, causes them to lag slightly so that the arm 24 swings away from j the stop pin 59. The spring 54 cushions and checks this movement, and as the rotation of the arm 22 gets under way, the centrifugal force swings the ,arm 24 back into alignment with ythe arm 22, at the same time causing the molten metal in the basin 26a to flow through the port 26b into the cavity 50a of the mold. But at whatever instant this ii'ow occurs, the position of the mentum is overcome by friction, or it is purposely arrested by the operator.

As already indicated, the spring 2 is tensioned vsufficiently by turning the arm 22 in a direction opposite to that in which itis to rotate during the castingv process. Even a partial turnwill store considerable energy in the spring, and when the spring has been wound sufficiently, in the judgment of the operator, the parts may be checked by lifting a stop pin 60 into engagement 7 with one of the notches 6I .in a plate 62 fixed to the upper end of the spindle AI3. A handle 63 is connected to` the pin 60 and extends outside the shell AI0 for lifting the pin, and when 5 it has been thus raised, the tension of the spring 2 serves to maintain plate 62 in engagement with the 4pin 60 until, when he is ready to start the machine in motion, the operator swings the arm 22 a few degrees back from its locked position, thus disengaging the notched plate from the pin 69 and allowing the latter to drop away from locking position by gravity or under the inuence of its own spring 64. The operator then releases the arm 22 to allow it to be rotated by the spring `2. After the device has rotated long enough, it may be arrested by means of a friction brake shoe normally held out. of ug contact with the spindle I3 by a spring 66,' but provided with a thumb-piece 61 outside the lshell I0 for manipulation atwill. t

Since the mold ring holderj39, with its :fingers or prongs 39", is designed to supporty only a limited range of sizes of mold rings, it is made readily removable` by loosening of the nut 33 so 2.0 that it maybe `replaced with a larger holder, if

a larger mold rring is to be employed. In the case of a mold ring of maximum size it may be that the inertia of these parts at the start of rotation lof the arm 22 may cause the floating arm 35 to swing about its pivotal connection to the arm 22 through a considerable'angle-perhaps as much as degrees; and to arrest vthe parts gently, under such circumstances, there may be provided a yielding bumper in the form of a plunger 10, carried in a guide sleeve 1| and backed by a spring 12 in the sleeve, which spring will be compressed when the bracket 24 bearsy againstvthe plunger 16 in swinging through its maximum angle. Inv any event, the bracket 24 and the arm 35 will be'returned promptlyrinto alignment with the arm 22 by means of the lriilial spring 54 acting about the axis of the 'ro insure that, as the molten metal sus the t the axis, the force acting outwardly on the molten metal then tends to cause it to climb in the mold, overcoming they force of gravity which, otherwise, would cause the metal to accumulate first in the lower portion ofthe mold cavity. By thus overcoming the gravitational effect I caiise themolten metal to be forced simultaneously against the, entire surface of the mold cavity. thus expelling the air from all parts of the mold by way of the porous material of which the mold is formed, and producing a casting of perfect form and sharp delineation. The desired inclinati the-plate 36 on which the mold ring 21 is mounted, and 'since the plate 36 is most conveniently. set at right angles to thearm 35, I attach this arm 35 to the, bracket plate 24 at a slight inclination to the horizontal, as seen in- Figs. 1 and 6.

As-seen in Figure 3, the trough of the crucible 26 is not exactly aligned with the axis `of the mold ring 21, but is disposed at a 'slight angle thereto, which increases the angularity vof the crucible trough with respect to the arm22 over that produced by the swinging lof the floating arm 35 about its hinge in response toinertia of the parts when the rotation commences. This insures an initial angularity at the rst instant of movement before even the force of inertia can .cause the parts respond by swinging of the mold may be secured by tilting,

about the hinged connection between the arms 22 and 35, and thus prevents any splashing or spillage of the molten metal over the sides of the crucible in this initial instant of rotation.

While there is shown and described herein certain specific structure embodying the invention, itwillbemanifesttothoseskilledintheart that various modifications and re-arrangements of the parts may be made without departing from the spirit and scope of the invention, and that the same is not limited to the particular form herein shown and described, except in so far as indicated by the appended claims. y

I claim asmy invention:

i. In a centrifugal casting machine, a spindle journaled for rotation about a vertical axis, a horizontal arm carried thereby, a crucible and mold supported by the arm ata distance from the axis of rotation, a balancing weight adjustable along the arm at the other sideof said axis, said spindle having a head formed with a bore through which the arm extends, said bore being largerthanthearmandtheheadhavingafulcrum onvwhich the arm may rock while the weight is adjusted to balancing position, a collet on the arm having a split tapered portion and a shank extending into the bore, and means for forcing said tapered portion of the collet into the bore of the spindle head to tighten the'collet on the arm and lock said arm in rigid relation to the spindle. Y 1

2. In a centrifugal casting machine, a spindie journaled for rotation about a vertical axis, a horizontal arm carried thereby, a crucible and mold supported by the arm at a distance from` the axis of rotation, a'balancing .weight adjustable along the arm at the other side of said axis, said spindle having a head formed with a bore through which the arm extends'.said bore being llarger than the arm and being flared at both ends, a horizontal pivot securing the arm in the head andV on which the arm may rock while the weight is adjusted to balancing position, a collet on the-arm having a split tapered portion and a threaded shank extending through the bore, and a nut on said shank having a portion to ilt into one flared end of the bore when the nut is tightened to draw' the tapered portion of the collet into the cpposite ared end of said bore for compressing the collet and locking the arm in rigid relation to the spindle.

'3. A centrifugal casting machine which includes an arm mounted iorrotation about an axis with a cruciblev and mold supported by the arm at a distance from the axis of-rotation and a balancing weight adjustable along the arm Vat the other side of said axis,- characterized by said arm having a groove of graduated depth dimetriishing toward the outer end of the arm, an a set screw in the weight adjustable to bear against the bottom of said groove for clamping the weight at adjusted position on the arm. 4. In a centrifugal casting machine, an arm mounted for rotation about a transverse axis, a mold support connected to said arm by pivotal means at a distance from said axis, and spring means reacting between `the pivotally connected parts and resiliently urging the mold to its maximum distance from the axisuof rotation.

5. In ,a centrifugal casting machine. an arm mounted for rotation about .a transverse axis, a mold support with pivotal 'means connecting said support to the arm at a vdistance from the axis of rotation to longer than the portion oi' the to the inertia of the pivoted parts when the arm begins to rotate, and spring means reacting between the arm and said pivoted support to cushion such swing of the support.

6. In a centrifugal casting machine. a horizontal arm mounted for rotation about a vertical axis. a mold support with a vertical pivot connecting said support to the arm at a distance from the axis of rotation to permit the support to swing'away from the direction of rotation in response to the inertia of the pivoted parts when the arm begins to stantly acting to urge the support yieldingly outward to its maximum distance from the axis of rotation, and stop positioned to limit the outward movement of the support.

7. In a centrifugal casting` machine. an arm mounted for rotation about a transverse axis, a mold support pivoted `to one end of said arm, a stop on the arm for limiting the swing oi' the mold support to a position substantially in alignment with the arm. and spring means limiting the swing of the mold support away from alignment to a position substantially at right angles to the arm.

8. In a centrifugal casting machine, a horizontal arm mounted for rotation about a vertical axis, a bracket in the form of a ilat plate hingedly connected to the end of said arm and extending upwardly therefrom in a vertical plane, a mold-carrying arm of cured to said bracket above the horizontal arm, and a crucible support including a tubular part telescopically engaged with the mold-carrying arm and having an elongated slot at its under side straddling the bracket plate, said slot being plate which it engages whereby the crucible support is held upright on the arm with capacity for sliding adjustment toward and from the mold. y

9. In a centrifugal casting machine, a horizontal arm mounted'for rotation about a vertical axis, a tubular arm connected thereto by a vertical pivot, a mold ring support carried ilxedly by said tubular arm, a crucible support including a tubular member telescopically ,engaged with dog within the tubular arm, but anchored to the slidable member by means extending through said slot, said dog havin; a tooth engageable with the inner surface of the tubular arm and a nut threaded on the slidable member in engagement with a portion of the dog and adjustable to rock the dog about its pivot and force the toothof said dog into clutching engagement f with the arm.

Permit the support to swing away from the direction of rotation in response l0. In a centrifugal casting machine which includes a horizontal arm iournaled for rotation avertical axis, the combination of means for supporting a crucible and mold thereon comprising a bracket platel extending in a vertical plane having one end bifurcated, the bifurcated terminals being bent into cylindrical form, a

braced by the cylindrical bracket terminals respectively, and threaded means clamping said bushings against opposite faces of said flat plate but permitting said bracket to swing freely on the hinge thus formed.

EMME'I'I' B. MOORE.

rotate. spring means con-- circular cross-section se 

